How can I undervolt these fans...? A unique scenario.

OK... This is the deal.

I bought this Koolance case, and planned on building my first completely silent system.

The case has 3 80mm fans built into the top. I assumed right off the bat that these fans would be louder than I wanted... (and I was right.) So the plan was to buy 3 80mm Panaflos and replace the stock fans with the Panaflos. So I did that... everything seemed fine.

The Koolance case runs the fans at three speeds. 1) Low speed until you hit 45*C, 2) Low speed until you hit 35*C, or 3) High speed all the time.

So I assumed that I could just pop the Panaflos in, and it would undervolt them on settings 1 and 2, and run them at full speed at setting 3.

Well... it didn't quite work that way. What happens is... it won't do anything on settings 1 and 2, and it runs them full speed on setting 3.

I noticed that while installing the Panaflos that they had a 2 pin connector. I thought that was a little odd, and I had to chip off one of the little teeth on the connector to get it to fit in the 3 pin socket. Now... the original fans had a 3 pin connector, but only two wires were in the connector, so I was hoping that there wouldn't be any difference between the original fans, (3 pin connector with only 2 wires) and the Panaflos (2 pin connector, 2 wires). But obviously there is a difference... I just don't know what it is. I read somewhere that the 2 pin connector has different traits than a 3 pin, (other than the whole "one less pin" thing. :P ) Is this true? Should I have gotten 3 pin Panaflos? Would that fix my problem?


Another odd thing is... When I found out that they wouldn't run at low speed, I plugged one of the old fans in, while the Panaflos were still plugged in. It ran at "low" speed (obviously), but I also noticed that the Panaflos were starting to move a little. They barely had any RPM's, but they were moving. So... when just the Panaflos are plugged in, they don't do a thing,... no "twitch" when it starts up.. no nuthin'... but if I plug one of the old fans in along with the Panaflos, then they at least try to move... and sometimes do for a little bit. (at very low RPM's).


My other solution is to undervolt the fans while they run at the full speed setting. So... if I have to do that, what's the easiest way to drop the 12v connectors down to 9v or 7v? I'd rather not use a rheostat, if at all possible. I know there are options for just using "rigged" connectors to do this, I'm just wondering what my best options are.

Any suggestions would be appreciated. I'm kinda thinking that the whole "2 pin" thing is the cause of the problem, because the fans I replaced were just normal 80mm fans... nuthin' special... so I would have assumed that the Panaflos would have worked just the same... but alas.. they don't... so do I need 3 pin panflos, or voltage regulation?

WATYF

You need to buy an adapter to use those panaflo fans. They call them tails.

You can get them here or most other places (newegg seems to be out)
http://directron.com/fantails.html

so the old fans only had 2 wires running from the connector? if that's the case, then it's odd that you're having this problem.. the 3 wires are +,-, and speed sensor, so that you can monitor the speed of the fan. a fan with 2 wires, just doesn't have a speed sensor. if the koolance uses the speed sensor for some reason in calculating how to regulate the fan speeds, than that would make a difference.. but you say that the original fans didn't have 3 wires... so that's out.

the second thing is that some fans respond better to undervolting than others do.. maybe the panaflows don't like how low the koolance is making it? unlikely, but possible.. i know that my 120mm sunons will not start at 5v. they will "twitch". at 7v they're fine though. but that possibility is also out, because there shouldn't be a difference between whether or not there is an original fan hooked up....

odd problem indeed... you should look over everything and make sure it is hooked up right.


to undervolt...
the 3 wires coming from the fan are usually red black and yellow. the feed (+) to the fan is the center connector, which will normall be red.
the black wire is always the ground (-)
the third wire, whatever color, is the speed sensor.. if your fan has it, you don't need it.. don't worry abuot it if you don't care what speed the fan is going.

the voltage that the fan runs on will be the difference between the - and the +. (the + needs to be larger than the -).

the 4 pin molexes coming from the power supply have 2 grounds (black), a 12v line (yellow), and a 5v line (red). so you have 2 convenient ways to undervolt your fans...

connect the + from the fan to the 5v line from the power supply, and the - from the fan to a ground (any black wire..)
your fan will run at 5v

you could also connect your + from the fan to the 12v line from the power supply, and the - from the fan to the 5v line from the power supply. the difference between the two is 7v, so that's what the fan will run at.


now, you can easily set up a toggle switch to change the voltage on the fan from 12v to 7v (or 5v.. but i'm going to tell you how for 7v).

hook the + from the fan directly to a 12v line from the power supply. then, hook the - from the fan to the center post (output) of the toggle switch. then, hook up a black wire (Ground) and red wire (5v) from the power supply to the other 2 posts on the toggle switch. this will alter your - on the fan between ground and 5v when you change the position of the switch, and the + stays at 12v... so you alter between the fan running at 12v and 7v.

that was long, but i hope it helped.. :)

OK... Well. I did some more tests...

The results are bad... and yet good. :p

It appears that all my other fans will run on Koolance's lower settings... the Panaflos are the only ones that won't. (go figger). That's the bad news.

The good news is that all my other fans, when run on the low setting, have extremely low RPMs. So low that they don't really push any air at all... which brings me to the conclusion that the Koolance speed control is not the way to go...

that said... it looks like I'm going to have to use some other kind of control to change the speed of the fans.

So.... I was looking at the BayBus. It looks like a relatively easy way to control all my fans. From what I understand, I can hook all three fans up to the BayBus, and just turn them up or down whenever I want to. If that's the case, then I would be willing to go that route. Does anyone here recommend anything other than the BayBus for an easy way to control a few fans? If not, then where's the best place to get a BayBus at... (in the US). I'm going to want a beige faceplate also, to go with it.


WATYF

i have the 3.5" baybus from vantec. it's ok, looks good, but i'm going to go back to the baybus i made out of 8 toggle switches and some plexi glass. that allows me to have fans at full speed, medium (7v), or off. the toggle switches also handle so many times more fans per switch that it's not even funny.. this 3.5" will handle about 3 80mm fans per rheostat. the 5" version handles more, and the sunbeam or whatever handles even more then that... but not as much as a toggle switch ;) ironically, i have so many toggle switches that i just use 1 fan on each switch... but still ;)
also, rheostats put heat back into your system.. not much, but some.

www.svc.com is a good place to get a baybus at, as are many other mod accessory sites...




but back to your problem with the panaflows.... how did you hook wires to the fans? any chance you messed up right there?

Might have been a wattage issue... ever think of that. Since 3 panaflos were plugged in they sucked the power right out of the connector. But since you took one away the two started working because the other fan took up less watts.

...i don't think he changed the number of fans he has total.. just replaced them

maybe i'm wrong... but that's what i've based my suggestions on so far

No... the fans came with tails. So it wasn't my wiring... and yes... during my tests I always had the same amount of fans hooked up (3).


It's ok... what I think I'm going to do is get me one of these.

I did some reading and it appears that the best and most convenient way to control multiple fans is using a rheobus. There are two major models available... the Nexus, and the Sunbeam. But it appears that there are longstanding issues with the Nexus, as being reported on Anandtech and OCForums, so I'm gonna go with the Sunbeam.

I think this will take care of my problem.


WATYF